Process for manufacturing olefinic hydrocarbons with respectively two and three carbon atoms per molecule
AssigneeInstitut Francais du Petrole
InventorsJean-Pierre Franck, Edouard Freund, Christian Marcilly, Jean Miquel
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Abstract
The present process has for object the manufacture of olefinic hydrocarbons with respectively 2 and 3 carbon atoms per molecule. This object is attained by treating a charge selected from such cuts as light or heavy naphthas, kerosenes and light gas oils of distillation point lower than 360.degree. C. The cut is subjected to hydrogenolysis and the resulting C.sub.2 and C.sub.3 hydrocarbons are fed to a steam-cracking plant, while the C.sub.4.sup.+ hydrocarbons are subjected to further hydrogenolysis.
Claims16
A process for manufacturing ethylene and propylene from a charge having a distillation point lower than about 360.degree. C. and containing at least normal and iso-paraffins having at least 4 carbon atoms per molecule, wherein:
- (a) said charge is subjected to a hydrogenolysis reaction in a hydrogenolysis zone, in the presence of a catalyst of the acid mordenite type with at least 0.01 to 25% b.w. of at least one group VIII metal,
- (b) the effluents from the hydrogenolysis reaction are fed to a separation zone from which are discharged (.alpha.), from the top, methane and possibly hydrogen, (.beta.) a fraction consisting essentially of hydrocarbons with 2 and 3 carbon atoms per molecule, and (.lambda.), from the bottom, a fraction consisting essentially of hydrocarbons with at least 4 carbon atoms per molecule,
- (c) only said fraction consisting essentially of hydrocarbons with 2 and 3 carbon atoms per molecule is fed to a steam-cracking zone, in the presence of steam, to transform at least a portion of the hydrocarbons with 2 and 3 carbon atoms per molecule to monoolefinic hydrocarbons;
- said fraction consisting essentially of hydrocarbons with at least 4 carbon atoms per molecule, obtained from the bottom of said separation zone, is supplied to a second hydrogenolysis zone where it is treated in the presence of a catalyst containing at least 0.01 to 25% b.w. of at least one metal of group VIII, VI B or VII B, the effluent from the second hydrogenolysis zone is supplied to a separation zone to discharge, on the one hand, hydrocarbons with at least 4 carbon atoms per molecule which are recycled at least partly to the said second hydrogenolysis zone, and, on the other hand, a fraction consisting essentially of a mixture of hydrogen, methane and saturated hydrocarbons with 2 and 3 carbon atoms per molecule;
- a hydrogen stream and a methane stream are separated from said mixture and there is fed to said steam-cracking zone the hydrocarbons of said mixture with 2 and 3 carbon atoms, together with said fraction consisting essentially of hydrocarbons with 2 and 3 carbon atoms per molecule as recovered from said separation zone following the first hydrogenolysis zone, and there are thus obtained at the outlet of the steam-cracking zone, in addition to a stream of methane and hydrogen and a stream of paraffinic hydrocarbons with 2 and 3 carbon atoms per molecule, on the one hand, olefins with 2 and 3 carbon atoms per molecule and, on the other hand, products with at least 4 carbon atoms per molecule.
A process for manufacturing ethylene from a hydrocarbon charge having a distillation range between 0 and 360.degree. C. and containing at least normal and iso-paraffins with at least 4 carbon atoms per molecule, wherein said charge is treated successively in at least 3 serially arranged hydrogenolysis or hydrocracking zones operated at a temperature between 300 and 550.degree. C., the temperature of each of said hydrogenolysis or hydrocracking zones, other than the first hydrogenolysis zone, exceeding by about 5 to 25.degree. C. the temperature of the hydrogenolysis zone previously traversed by the charge, said first hydrogenolysis or hydrocracking zone traversed by the charge containing a catalyst of the acid mordenite type containing 0.01 to 25% of at least one metal from group VIII of the periodic chart of the elements selected from nickel, cobalt and iron, the other said hydrogenolysis zones containing 0.01 to 25% of at least one noble metal of the platinum family deposited on a carrier, which carrier is selected from silicas, aluminas, alumina-silicas, zeolites and mordenites, the effluent from each hydrogenolysis zone being subjected to a series of separations, so as to collect, in addition to a stream of hydrogen and a stream of methane, on the one hand, a cut consisting essentially of ethane and propane and, on the other hand, a cut of C.sub.4.sup.+ hydrocarbons having 4 or more carbon atoms per molecule, said C.sub.4.sup.+ cut being either fed to the subsequent hydrogenolysis zone or, if said C.sub.4.sup.+ cut is that discharged from the last hydrogenolysis zone traversed by the charge, recycled to at least one of the preceding hydrogenolysis zones, all the cuts consisting essentially of ethane and propane being joined and supplied to a steam-cracking zone, in the presence of steam, the effluent from the steam-cracking zone being supplied to a separation zone, from which are discharged:
- (a) a stream of methane and hydrogen which is at least partly recycled to said series of separations of the effluents from the hydrogenolysis zones,
- (b) a stream consisting essentially of unconverted ethane and propane, which is recycled to the stream-cracking zone,
- (c) ethylene,
- (d) propylene,
- (e) hydrocarbons formed during the steam-cracking reaction and comprising at least 4 carbon atoms per molecule, which are at least partly recycled to at least one of the hydrogenolysis reaction zones.
Dependencies are inferred from the claim text.